Glenn Fleishman (of GlennLog) posts an interesting summary of his discussion with Howard Rheingold about Intentional or Implicit Rating. This is something near and dear to my heart as well, though I dream of the type of rating by action, I think that once we have the AI required to get there (and correctly interpret my actions) we may already have the AI required to correctly guess my actions and figure out ratings from my previous (and unrelated) information dump to the AI. Of course another response is that there is a third way (what GrepMoodMusic uses) that takes intentional ratings and then uses knowledge about those ratings to make a few of them go a long way.